Fabrication and characterization of TiO₂/ZrO₂ ceramic membranes for nanofiltration

TiO₂/ZrO₂ ceramic nanofiltration membranes are successfully fabricated through the polymeric sol–gel route followed by the dip-coating technique. Disk type α-alumina supported mesoporous γ-alumina (pore size: 5–6 nm) is employed as the support in dip-coating. The unsupported and supported composite ceramic membranes are systematically characterized and evaluated in terms of phase composition, chemical stability, gas adsorption, molecular weight cut-off (MWCO), membrane pore size, water flux and salt rejection. It is found that the TiO₂/ZrO₂ ceramic membranes have amorphous phase at 400 and 500 °C, suggesting the high thermal stability. The fabricated membranes have the MWCO of 620–860 Da, corresponding to the membrane pore size of 1.2–1.5 nm. Relatively low water permeability can be attributed to the low microporosity of the membrane. Donnan exclusion is the dominant transport mechanism of the NF membrane in the single-component system, and salt rejection is closely related to the hydration properties of the ions (e.g., the hydration radius).